From: mark <markkicks@gmail.com>
To: Justin <justin@emproshunts.com>
Cc: pgsql-general@postgresql.org
Cc: pgsql-performance@postgresql.org
Subject: Re: select query takes 13 seconds to run with index
Date: Mon, 26 May 2008 16:32:50 -0700
Message-ID: <82fa9e310805261632y46f306fdh84e2da62ffbd7873@mail.gmail.com> (raw)
In-Reply-To: <483B4729.7050402@emproshunts.com>
References: <82fa9e310805261549m2362fbe8sbf18789938fee833@mail.gmail.com>
<483B4729.7050402@emproshunts.com>
On Mon, May 26, 2008 at 4:26 PM, Justin <justin@emproshunts.com> wrote:
> mark wrote:
>> Hi, is there anyway this can be made faster? id is the primary key,
>> and there is an index on uid..
>> thanks
>> EXPLAIN ANALYZE select * from pokes where uid = 578439028 order by id
>> DESC limit 6;
>> QUERY
>> PLAN
>>
>> ----------------------------------------------------------------------------------------------------------------------------------------------------
>> Limit (cost=0.00..9329.02 rows=6 width=135) (actual
>> time=13612.247..13612.247 rows=0 loops=1)
>> -> Index Scan Backward using pokes_pkey on pokes
>> (cost=0.00..5182270.69 rows=3333 width=135) (actual
>> time=13612.245..13612.245 rows=0 loops=1)
>> Filter: (uid = 578439028)
>> Total runtime: 13612.369 ms
>> (4 rows)
> First this should be posted on performance list.
sorry about this.
> how many records are in this table?
22334262, 22 million records.
> The estimate is way off, when was the last time Vaccum was on the table?
about a week ago i ran this VACUUM VERBOSE ANALYZE;
this table is never updated or deleted, rows are just inserted...
> What verison of Postgresql are you running
8.3.1
> Size of the Table
22 million rows approximately
> Table layout
CREATE TABLE pokes
(
id serial NOT NULL,
uid integer,
action_id integer,
created timestamp without time zone DEFAULT now(),
friend_id integer,
message text,
pic text,
"name" text,
CONSTRAINT pokes_pkey PRIMARY KEY (id)
)
WITH (OIDS=FALSE);
ALTER TABLE pokes OWNER TO postgres;
-- Index: idx_action_idx
-- DROP INDEX idx_action_idx;
CREATE INDEX idx_action_idx
ON pokes
USING btree
(action_id);
-- Index: idx_friend_id
-- DROP INDEX idx_friend_id;
CREATE INDEX idx_friend_id
ON pokes
USING btree
(friend_id);
-- Index: idx_pokes_uid
-- DROP INDEX idx_pokes_uid;
CREATE INDEX idx_pokes_uid
ON pokes
USING btree
(uid);
> Load on the database
how do i measure load on database?
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To: pgsql-performance@postgresql.org
Cc: markkicks@gmail.com, justin@emproshunts.com, pgsql-general@postgresql.org
Subject: Re: select query takes 13 seconds to run with index
In-Reply-To: <82fa9e310805261632y46f306fdh84e2da62ffbd7873@mail.gmail.com>
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